1. Update on Version Control Systems: GitLab, SVN, Git, Trac, CERNforge
Alexandre Lossent
IT-PES-IS
5th LHCb Computing Workshop, 22 May 2015

2. Version Control Systems in use at CERN
Central SVN service
Access control, CERN accounts, e-groups
Central Git service
git.cern.ch and now GitLab (gitlab.cern.ch)
Github
Nowadays de-facto standard for Open Source projects with external partners
Some projects mirror their repos at CERN
Other private installations
Git, SVN, Stash etc.
Smaller groups with specific needs (and system resources)
Should not be visible on the Internet
5th LHCb Computing Workshop, 22 May 2015

3. Improving Central VCS offering at CERN
Looking for solutions to typical challenges
How to ensure the quality of new features/fixes?
How to decide if the code is ready for production?
How to manage concurrent work and merge conflict resolution?
How to be confident that code working on a dev’s machine will work as expected after deployment?
How to enable contributions from outside the core dev team without risking damage to the code repository?
Making it easier to create and manage code repositories
And streamline integration with related services: Issue Tracking, Continuous Integration, Documentation…
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Why deploy GitLab?
Complement Version Control Services with new features to help developers implement software development best practices
Provide a mean to review code and test results, discuss and take decision whether to merge code
Associate code changes with a ticket in an Issue Tracking system– Provide code review features to help improve code quality
Encourage collaboration by enabling project forks and merge requests
Make it easier to run tests with Continuous Integration platforms
Well-defined roles within a project or group of projects
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5. 5th LHCb Computing Workshop, 22 May 2015
GitLab project page
5th LHCb Computing Workshop, 22 May 2015

6. GitLab repository browsing
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GitLab graphs
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8. GitLab code review: Merge Request
5th LHCb Computing Workshop, 22 May 2015

9. GitLab feature summary
On-premise “GitHub lookalike”
Version Control based on Git
With SSH support & SSH key authentication
Hierarchical project (= repository) organization
Groups – contain multiple projects for a given team
Personal workspace – removed when user leaves CERN, a la home directory
Code browsing
Including editing files from the web interface
Code review workflow
Important branches are protected
Changes submitted from feature branches or project forks
Merge Requests reviewed by “master” developers before being merged
Self-service
One-click project creation, repository immediately available to work with
Integration
Global CERN services: SSO, SSH keys, mapping of E-groups to roles…
Developer services: Jira, Jenkins (a Continuous Integration platform)…
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10. 5th LHCb Computing Workshop, 22 May 2015
Git, GitLab and Github
GitLab is now in production and recommended
Provides additional features compared to git.cern.ch (Gitolite-based)
collaboration and code review features
Recommended for all new version control projects hosted at CERN
To get started: KB
Librarians can move repositories from git.cern.ch to GitLab: KB
Git.cern.ch is no longer recommended for new projects
Self-service requests for new projects will be moderated from 1 Jul 2015
Longer term future of git.cern.ch will be evaluated at a later stage
Github.com may be appropriate
For open source and projects with external collaborators
GitLab at CERN supports CERN accounts only
Advice on choosing between CERN GitLab and GitHub.com: KB
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11. 5th LHCb Computing Workshop, 22 May 2015
SVN Service
SVN will continue for established projects
Maintenance updates but no additional development is planned
New projects are encouraged to use GitLab
New SVN repository requests will be moderated from 1 Jul 2015
Migration from SVN to GitLab will be possible
Librarians will be contacted in due time to discuss potential migrations
The Trac add-on to SVN will be maintained for code browsing in projects already using it
JIRA, web services (e.g. Twiki) are recommended for tickets, wiki, etc
The recommended SVN web interface is websvn
Jira migration instructions will be provided for those who wish to do so
Issues raised in the May Trac survey are being followed up with users
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JIRA Service
JIRA currently hosts ~540 projects
Upgrade from JIRA to 6.4.x is planned
During summer or early autumn
Fisheye/Crucible server will be stopped at end of 2015
Has problems with scalability
Less user friendly than GitLab for code review
Recommended replacement is GitLab
Affects relatively few users
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CERNforge
CERNforge
Portal for creating and managing resources related to code management
Has been updated to reflect changes to the Git, GitLab, SVN and JIRA services outlined on the previous slides
5th LHCb Computing Workshop, 22 May 2015

14. Software Development Workflow*
Issues/requests
Jenkins job
Users
GITLAB
Commit changes
Developers
Software Release
Internal Software Build
SVN
GIT
Test
Results
Release
Build
Automatic tests
Review & Merge
*This is a simplified example of a possible workflow with the supported tools [Thanks to Manuel Gonzalez Berges (EN-ICE) for this slide]
5th LHCb Computing Workshop, 22 May 2015

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GitLab: good to know
The code review workflow replaces fine-grained permissions: KB
GitLab has just a few predefined roles: Guest, Developer, Master, Owner
Branches have a ‘protected’ flag (on for master by default) to:
Prevent force push and branch deletion
Force developers to use feature branches and the code review workflow
SSH access via nonstandard port 7999: KB
Available from outside CERN. Copy URL from project page!
The Public visibility level really is public: KB
Worldwide anonymous access, incl. search engines
no “CERN Public” visibility level!
Use SSH Deploy Keys for automated pull operations (build, deploy jobs etc.): KB
Don’t forget to add [gitlab.cern.ch]:7999 to known_hosts
E-groups can be used at the Group level, but not for individual projects
I.e. all projects in a group are more or less expected to share same permissions.
Workarounds possible. A future KB article will cover this.
5th LHCb Computing Workshop, 22 May 2015

16. Summary of GitLab resources
Getting started: KB
Set up SSH keys: KB
Permissions in GitLab: KB
Moving repositories from git.cern.ch to GitLab: KB
Other KB articles: see GitLab topic in the Service Portal
GitLab help:
Feedback & support: Git Service in the Service Portal
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Questions?
5th LHCb Computing Workshop, 22 May 2015